• Tunnel and Underground Space
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• v.7 no.2
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• pp.116-129
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• 1997

The objective of this study is to predict the minimization effect of the noise and vibration during the construction and the train operation regarding to the design modification of the Taegu Subway Line No. 1. It was suggested optimal control blasting methods to reduce the causing vibration Nuance to the resident in City Taegu and also proposed the better governing method to decrease the environmental hazard to the near buildings and residents during the train operation. When the high-density gaseous reaction of explosion products exerts a high pressure in motion outward, a dynamic stress field will be created in the surrounding buildings. Therefore, in the region close to the charge, permanent damage begins to occur at a great critical level of partial velocity, that is difficult from different structure as working conditions. It is reliable to predict that the damages could be reduced if we know the peak velocity and the exact reasons through the conducting of detail studies of structural analysis of the related buildings with the optimal blasting designs. A blasting technique should be deemed to take advantage of the reduction of damage of the surrounding rocks and structures to improve the in-city blasting. This is a typical in-city blasting operation where success depends on closely controlling the ground vibrations in case of better designed blasting methods. There are techniques that can be applied to prevent large vibrations from damaging the important buildings through the Route Modification of the Taegu Subway Line No. 1.

• Journal of Environmental Science International
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• v.27 no.6
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• pp.467-475
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• 2018

The lifetime of the electrode is one of the most important factors on the stability of the electrode. Since the lifetime of the DSA (Dimensionally stable anode) electrode is long, an accelerated lifetime test is required to reduce the test time. Beacuse there is no basis or standard method for accelerated lifetime testing, many researchers use different methods. Therefore, there is a need for basis and methods for accelerated lifetime testing that other researchers can follow. We designed a reactor system for accelerated lifetime testing and planned specific methods. Reactor system was circulating batch reactor. Reactor volume and cooling water tank were 12.5 L and 100 L, respectively. Electrode size was $2cm{\times}3cm$ (real electrolysis area, $5cm^2$). In order to maintain the harsh conditions, accelerated lifetime test was carried out in a high current density ($0.6A/cm^2$) and low electrolyte concentration (NaCl, 0.068 mol/L). Maintaining a constant temperature was an important operation parameter for exact accelerated lifetime test. As the accelerated lifetime test progressed, the active component of electrode surface was consumed and desorption occurred. At the point of 5 V rise, corrosion of the surface of the base material(titanium) also started.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.7
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• pp.100-114
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• 1996

In order to create a solid model more efficiently for a plastic or sheet metal product with a thin and constant thickness, various methods have been proposed up to now. One of the most typical approaches is to create a sheet model initially and then transform it into a solid model automatically for a given thickness. The sheet model as well as the transitive model in sheet modeling procedure is a non-manifold model. However, the previous methods adopted the boundary representations for a solid model as their topological framework. Thus, it is difficult to represent the exact adjacency relationship between topological entities and to implement the topological operations for sheet modeling and the transformation procedure of a sheet into a solid. In this paper, we proposed a sheet modeling system based on a non-manifold topological representation which can represent solids, sheets, wireframes, and their mixture. A set of generalized Euler operators for non-manifold topology as well as the sheet modeling capabilities including adding, bending, and punching functions are provided for easy modeling of sheet objects, and they are perfomed interactively with a two dimensional curve editor. Once a sheet model is completed, it can be transformed into a solid automatically. The transformation procedure is composed of the offset functions and the Boolean operations of sheet models, and it is even more comprehensive and easier to be implemented than the precious methods.

• Journal of the Korea Society of Computer and Information
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• v.3 no.2
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• pp.85-97
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• 1998

The existing edge detection methods can not represent the real edge of object at fitting point or detect the edge which has unsufficient connecting trait. Especially, the two-fold thick edge detected by these methods cannot coincide real boundary of subject and it's location. To overcome these problems, we introduce the Genetic Algorithm(GA) in edge detection. The energy function is the value of fixel's satisfaction degree to edge condition. And it consists of the fitness value to image formation type, fitness value to connecting trait to it's neighboring edge and evalulation function which can represents the edge at fitting point as one fixel. This method is superior to remove the noise in edge detection than the existing methods. And it also detects the clear and exact edge because it can find the one fixel which is located at fitting point and has strong connecting trait.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1466-1472
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• 2010

In order to construct extremely large scale of sea dike like Saemanguem dike, extremely large amount of mass of rock are needed. In this case, it is general methods to estimate required amount of rock mass based on characteristics of consolidation settlement and bearing capacity of seabed, because it is impossible to estimate exact amount of rock material based on varied seabed condition.. Even in this general methods, it is very few case to manage rock mass amount by estimation of actual input rock mass but the main point is focused on the final section formation considering of designed section and reserve embankment, so excessive or underestimating result of rock mass would be occurred surely. This general methods is not resonable in the points of economic and stable. In this study, optimum construction management method of rubble mound in the 3rd section construction of Saemanguem sea dike is suggested based on comparing required rock mass estimating from consolidation settlement theory with actual input rock mass. It is found out that the optimum input quantity of rock mass is about $1,900{\sim}2,000m^3$/day.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.1
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• pp.127-135
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• 1991

This study purports to make in consideration of the recent xeroradiographic development an exact analysis, by comparison, of conventional cephalometry and xeroradiographic cephalometry that are indispensably utilized in the field of orthodontics as a means of cephalometric measuring For that purpose attached to ten landmarks on a dry skull was a lead ball, a radio-opaque substance, and projected X-ray beam one time each by means of the two methods, and then ten times each without change of locations of the skull, in the state in which the lead ball was removed. These data were committed to ten dentists for tracing to determine a difference between the same kind of cephalometries. A computerized statistic analysis of the data shows findings, as follows: 1. Conventional cephalometry shows higher accuracy in Nasion, as compared with xeroradiographic cephalometry. 2. Xeroradiographic cephalometry is found more accurate in Anterior Nasal Spine, 'A' Point, Pogonion, Gonion, Porion, Prosthion and Orbitale than conventional cephalometry. 3. There is no difference between both methods in Basion. 4. At test between the two methods by all the dentists reveals that xeroradiographic cephalometry is more accurate than conventional cephalometry.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.742-746
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• 2010

In this paper, we propose new randomness testing methods based on approximate periods in order to improve the previous randomness testing method using exact pattern matching. Finding approximate periods of random sequences enables us to search similarly repeated parts, but it has disadvantages since it takes long time. In this paper we propose randomness testing methods whose time complexity is O($n^2$) by reducing the time complexity of computing approximate periods from O($n^3$) to O($n^2$). Moreover, we perform some experiments to compare pseudo random number generated by AES cryptographic algorithms and true random number.

• Journal of Internet Computing and Services
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• v.1 no.1
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• pp.1-14
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• 2000

Visual information retrieval and image databases are very important applications of spatial access methods. The quaries for these applications are visual and based not on exact match but on dubjective similarity. The individual aperations of spatial access methods are much more expensive than those of conventional one-dimensional access methods. Also, because the visual queries are much more complex than textual queries, an efficient processing technique for visual queries is one of the critical requirements in the development of large and scalable image databases. Therefore, efficient translation and execution for the complex visual queries are not less important than those of textual databases. In this paper, we introduce our cognitive and topological studies that are required to process subjective visual queries effectively. Then, we propose an efficient translation and execution techniques for similarity based visual queries by conducting these related studies.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.6
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• pp.607-613
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• 2009

A new formulation of NDIF method to the algebraic eigenvalue problem is introduced to efficiently extract natural frequencies of arbitrarily shaped plates with the simply supported boundary condition. NDIF method, which was developed by the authors for the free vibration analysis of arbitrarily shaped membranes and plates, has the feature that it yields highly accurate natural frequencies compared with other analytical methods or numerical methods(FEM and BEM). However, NDIF method has the weak point that it needs the inefficient procedure of searching natural frequencies by plotting the values of the determinant of a system matrix in the frequency range of interest. A new formulation of NDIF method developed in the paper doesn't require the above inefficient procedure and natural frequencies can be efficiently obtained by solving the typical algebraic eigenvalue problem. Finally, the validity of the proposed method is shown in several case studies, which indicate that natural frequencies by the proposed method are very accurate compared to other exact, analytical, or numerical methods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.113-119
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• 2005

The methods that are used for receiving data from attached devices under real-time preemptive multi-task operating system (OS) by general processors can be categorized as polling and interrupt driven. The technical approach to these methods may be different due to the application specific scheduling policy of the OS and the programming architecture of the flight software. It is one of the most important requirements on the development of the flight software to process the data received from satellite subsystems or components with the exact timeliness and accuracy. This paper presents the analysis of the I/O method of device related scheduling mechanism and the reliable data I/O methods between processor and devices.